UV-INDUCIBLE PROTEINS AND UV-INDUCED CROSS-PROTECTION AGAINST ACID, ETHANOL, H2O2 OR HEAT-TREATMENTS IN LACTOCOCCUS-LACTIS SUBSP LACTIS

The relationship between UV-irradiation-induced tolerance to different environmental stresses and change in protein synthesis was examined in Lactococcus lactis subsp lactis IL1403. The results showed that preirradiation of cultures of L. lactis subsp. lactis with UV254nm light led to increased tolerance of usually lethal challenges to acid (pH4.0), ethanol (20%, v/v), H2O2 (15 mM), or heat (52 degrees C). This suggests that there is an overlapping regulation between the UV-induced pathway and the other stress responses. Whole-cell protein extracts from UV-treated (100J/m(2)) and untreated cultures were compared using two-dimensional polyacrylamide gel electrophoresis. At least 14 polypeptides were induced in response to damage after UV irradiation, which indicated an SOS-like response in this species. The RecA protein, however, seemed not to be significantly induced in Lactococcus lactis subsp. lactis IL1403. Some of the UV-induced polypeptides overlaped with stress proteins induced by the other treatments.